Metagenomic Study of the African Fruit Straw-Colored Bat Virome
A large number of viruses that cause human disease have zoonotic reservoirs that are often unknown and poorly studied. This makes the complete control of their spread and eradication difficult. Identification of the animal reservoirs of these viruses will improve public health efforts at eradication of viral diseases like SARS, Dengue Fever, Lassa Fever. Additionally, some of the new emerging infectious diseases (EIDs) are caused by viruses whose origins/reservoirs are yet to be identified. Bats are natural resevoirs for viruses like Lyssaviruses, filoviruses, SARS-like coronaviruses and other viruses making them an ideal ''Eidolon helvum'' E. helvum is a large fruit bat found in sub-saharan Africa, Madagascar and the southwestern Arabian Peninsula. These frugivorous bats live in large colonies (100,000-1,000,000 bats) near people in urban areas. Although these bats are nocturnal feeders, they are usually awake and active during the day. Fruit bats are hunted and eaten as bush meat in certain parts of the African continent and their proximity to populated places also makes them potential carriers of zoonotic diseases and EIDs. As such, it is important to determine which if any human pathogens they may carry. Because viruses are responsible for about 25-45% of EIDs, approximately 80% of which have zoonotic origins in wildlife, it is essential to determine which wildlife carry potential EIDs. This will enhance efforts to control transmission of zooonotic EIDs (1). Why Bats? THey are reservoirs for a number of viruses that cause diseases in humans eg. SARS-like coronaviruses, some of the lyssaviruses, henipaviruses and filoviruses. Recently, bats have also been shown to be highly probable natural reservoirs for paroxyviruses. Thus, it is important to determine which viruses are associated with deifferent bat species to enable proper public health measures to be undertaken and also educate the public. Metagenomic Analysis Refers to the analysis of genetic material collected from environmental sources. In this study, Baker et al (2) took urine, throat swabs and lung samples from frugivorous bats from Ghana, West Africa. Sample collection: Swabfuls of urine were collected from tarps placed under the roosting areas of the bats while throat swabs were obtained from immobilized live bats and lung pieces were taken from euthanized bats. Total nucleic acids were extracted from pooled urine, throat and lung samples from which cDNA was generated by reverse transcription and subsequent complementary strand synthesis. The cDNA thus generated were then amplified by PCR and sequenced using next generation sequencing. Assembly of sequences from samples: Contigs from the individual samples were de novo assembled using the Velvet, AByss, MetIDBA and MetaCortex assemblers using the pipeline illustratef in figure 1. The initial contig sets obtained where then consolidated using sequential BLAT alignments in addition to the exclusion of short contigs. A large number of herpesvirus sequences related to different family members were identified in the throat samples and these are presented in figure 2, among the sequences identified was a novel gammaherpes virus as well as a number of bat betaviruses. A varying number of contigs were obtained by the different assemblers before they were consolidated. Overall, viruses from the viral families, Papilloma, herpes, Pox, retro, Parvo, picoma and a novel adenovirus were identified during this analysis (Table 3). Some of the viruses identified in the african fruit bat were very similar in sequence to the human pathogenic viruses thus validating the need to determine which human pathogens are carried by the bats which are consumed by people as bushmeat and also live in such close proximity to urban residences. Additionally this study provided new knowledge on the types of chiropetran viruses for which different species of bats serve as reservoirs. References #Jones KE, Patel NG, Levy MA, Storeygard A et al. (2008) Global trends in emerging infectious diseases. Nature 451, 990-993http://www.nature.com/nature/journal/v451/n7181/full/nature06536.html http://www.nature.com/nature/journal/v451/n7181/full/nature06536.html #Baker KS, Legett RM, Bexfield NH et al., (2013) Metagenomic study of the viruses of African straw-coloured fruit bats: detection of a chiropteran poxvirus and isolation of a novel adenovirus. Virology 441(2):95-106 http://www.sciencedirect.com/science/article/pii/S0042682213001542 #http://www.arkive.org/straw-coloured-fruit-bat/eidolon-helvum/ #http://en.wikipedia.org/wiki/Straw-coloured_fruit_bat